Composite seals for turbomachinery

ABSTRACT

The present application provides composite seals for reducing leakages between adjacent components of turbomachinery. The composite seals may include a metallic shim, a metallic support structure and a ceramic, glass or enamel coating. The shim and the support structure may be bonded or fused together. The support structure may include internal voids or gaps, and the coating may be applied to the shim and the support structure such that the coating is provided within the voids or gaps of the support structure, between portions of the support structure and the shim, and substantially over the outer surface of the support structure. The support structure may thereby provide a mechanical attachment between the shim and the coating. In use, the coating provides thermal and/or chemical insulation to the metallic shim and the support structure of the seal.

BACKGROUND OF THE INVENTION

The present application relates generally to seals for reducing leakage, and more particularly to seals configured to operate within a seal slot to reduce leakage between adjacent stationary components of turbomachinery.

Leakage of hot combustion gases and/or cooling flows between turbomachinery components generally causes reduced power output and lower efficiency. For example, hot combustion gases may be contained within a turbine by providing pressurized compressor air around a hot gas path. Typically, leakage of high pressure cooling flows between adjacent turbine components (such as stator shrouds, nozzles, and diaphragms, inner shell casing components, and rotor components) into the hot gas path leads to reduced efficiency and requires an increase in burn temperature, and a decrease in engine gas turbine efficiency to maintain a desired power level as compared to an environment void of such leakage. Turbine efficiency thus can be improved by reducing or eliminating leakage between turbine components.

Traditionally, leakage between turbine component junctions is treated with metallic seals positioned in the seal slots formed between the turbine components, such as stator components. Seal slots typically extend across the junctions between components such that metallic seals positioned therein block or otherwise inhibit leakage through the junctions. However, preventing leakage between turbine component junctions with metallic slot seals positioned in seal slots in the turbine components is complicated by the relatively high temperatures produced in modern turbomachinery. Due to the introduction of new materials, such as ceramic-matrix composite (CMC) turbine components, that allow turbines to operate at higher temperatures (e.g., over 1,500 degrees Celsius) relative to traditional turbines, conventional metallic turbine slot seals for use in seal slots may not be adequate.

Preventing leakage between turbine component junctions with metallic seals is further complicated by the fact that the seal slots of turbine components are formed by corresponding slot portions in adjacent components (a seal positioned therein thereby extending across a junction between components). Misalignment between these adjacent components, such as resulting from thermal expansion, manufacturing, assembly and/or installation limitations, etc., produces an irregular seal slot contact surface that may vary in configuration, shape and/or magnitude over time. Such irregularities in the seal slot contact surface allow for leakage across a slot seal positioned within the seal slot if the seal does not flex, deform or otherwise account for such irregularities. Unfortunately, many conventional metallic shims that account for such irregular seal slot contact surfaces due to misalignment of adjacent turbine components may not adequately withstand increases in operating temperatures of turbines.

Accordingly, composite turbomachinery component junction seals configured for use in typical turbine seal slots that withstand the increasingly higher operating temperatures of turbines and conform to irregularities in the seal slot contact surface would be desirable.

SUMMARY OF THE INVENTION

In a first aspect, the present disclosure provides a seal assembly for positioning within a seal slot formed at least partially by adjacent turbomachinery components to seal a gap extending between the components. The seal assembly includes a metallic shim, a porous metallic support structure, and a ceramic, glass or enamel coating. The metallic shim includes a sealing surface and a support surface. The porous metallic support structure is bonded to the support surface of the metallic shim. The ceramic, glass or enamel coating extends over and within the porous metallic support structure such that the coating substantially covers the support surface side of the metallic shim and the support structure. Portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure.

In some embodiments, portions of the coating may be positioned between the support surface of the metallic shim and portions of the metallic support structure in a direction extending away from the support surface to mechanically couple the coating to the metallic shim via the metallic support structure. In some such embodiments, the direction extending away from the support surface may be substantially normal to the support surface.

In some embodiments, the metallic shim may be a substantially solid metallic shim. In some embodiments, the coating may be chemically bonded to the support structure. In some embodiments, at least one of the support surface of the metallic shim and the metallic support structure may include a protective outer coating configured to prevent oxidation of the respective metallic component. In some embodiments, the metallic support structure may be diffusion bonded to the metallic shim via at least one braze. In some embodiments, the metallic support structure may be a mesh structure. In some embodiments, portions of the coating may be positioned between the support surface of the metallic shim and portions of the metallic support structure that are bonded to the support surface of the metallic shim.

In some embodiments, portions of the coating may be positioned between the support surface of the metallic shim and portions of the metallic support structure that are not bonded to the support surface of the metallic shim. In some such embodiments, portions of the metallic support structure that are not bonded to the support surface of the metallic shim may extend from or are coupled to portions of the metallic support structure that are bonded to the support surface of the metallic shim.

In some embodiments, the coating may be bonded to at least one of the support surface of the shim and the support structure. In some embodiments, the seal assembly may further include a second porous metallic support structure bonded to the sealing surface of the shim, and a second ceramic, glass or enamel coating extending over and within the second porous metallic support structure such that the second coating substantially covers the sealing surface side of the metallic shim and the second support structure, and portions of the second coating may be positioned between the sealing surface of the metallic shim and portions of the second metallic support structure.

In another aspect, the present disclosure provides a method of forming a seal assembly for use within a seal slot formed at least partially by adjacent turbomachinery components to seal a gap extending between the components. The method includes bonding at least one portion of a porous metallic support structure to a metallic shim. The method further includes applying ceramic, glass or enamel coating material to the porous metallic support structure such that the coating material overlies the support surface side of the metallic shim and the support structure, and includes portions that are positioned between the support surface of the metallic shim and portions of the metallic support structure. The method also includes densifying the ceramic, glass or enamel coating material to form a ceramic, glass or enamel coating mechanically fixed to the metallic shim via the metallic support structure.

In some embodiments, bonding at least one portion of the metallic support structure to the support surface of the metallic shim may include diffusion bonding at least one portion of the metallic support structure to the support surface of the metallic shim. In some embodiments, applying ceramic, glass or enamel coating material to the porous metallic support structure may comprise applying a high viscosity castable ceramic composition by screen printing or toweling. In some such embodiments, the method may further include removing a portion of the ceramic composition applied to the support structure via a doctor blade, and wherein densifying the ceramic composition comprises curing and heat treating the applied ceramic composition. In some embodiments, applying ceramic, glass or enamel coating material to the porous metallic support structure may comprise applying a glass or enamel based composition in a paintable form by painting, dip coating or spray coating. In some such embodiments, densifying the glass or enamel based composition may comprise drying and heat treating the applied glass or enamel based composition.

In another aspect, the present disclosure provides a turbomachine that includes a first turbine component and a second turbine component adjacent the first turbine component, the first and second turbine components forming at least a portion of a seal slot extending across a gap between the turbine components. The turbomachine further includes a seal positioned within the seal slot of the first and second turbine components and extending across the gap therebetween. The seal comprises a metallic shim, a porous metallic support structure, and a ceramic, glass or enamel coating. The metallic shim includes a sealing surface and a support surface. The porous metallic support structure is bonded to the support surface of the metallic shim. The ceramic, glass or enamel coating is provided on and within the metallic support structure such that the coating substantially covers the support surface side of the metallic shim and the support structure, and portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure.

In some embodiments, the ceramic, glass or enamel coating of the seal may be positioned against a first side of the seal slot that is collectively formed by a first side of the first turbine component and a first side of the second turbine component. In some embodiments, the metallic shim is a substantially solid metallic shim, and the porous metallic support structure is a metallic mesh structure. In some embodiments, portions of the coating may be positioned between the support surface of the metallic shim and portions of the metallic support structure in a direction extending substantially normal to the support surface to mechanically couple the coating to the metallic shim via the metallic support structure.

These and other objects, features and advantages of this disclosure will become apparent from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of a first exemplary slot seal assembly according to the present disclosure;

FIG. 2 is a perspective view of the exemplary slot seal of FIG. 1 partially assembled to illustrate the arrangement of the shim, support structure and coating portions;

FIG. 3 is a perspective view of the shim and support structure sub-assembly of the exemplary slot seal of FIG. 1;

FIG. 4 is an enlarged perspective view of a portion of the shim and support structure sub-assembly of FIG. 3;

FIG. 5 is an enlarged cross-sectional view of a portion of the shim and support structure sub-assembly of FIG. 4;

FIG. 6 is a side cross-sectional view of an exemplary slot seal assembly positioned within a seal slot to seal an exemplary junction between turbine components; and

FIG. 7 is a side cross-sectional view of an exemplary slot seal assembly.

DETAILED DESCRIPTION

When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters are not exclusive of other parameters of the disclosed embodiments. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular seal embodiment may similarly be applied to any other seal embodiment disclosed herein.

Composite turbomachinery component junction seals configured for use in turbine seal slots (e.g., composite turbine slot seals), and methods of manufacturing and using same, according to the present disclosure are configured to withstand the relatively high operating temperatures of turbines including CMC components and/or conform to irregularities in the seal slot contact surface. In particular, the composite slot seals are configured to substantially prevent chemical interaction and substantially limit thermal interaction of metallic components of the composite slot seals with the hot gas flow/leakage and/or the seal slot itself. In this way, the composite slot seals provided herein allow for use in high temperature turbine applications. In addition to high temperature operation, the composite slot seals of the present disclosure are configured to conform to irregularities on the seal slot contact surface to decrease leakage due to seal slot surface misalignment and/or roughness.

As shown in FIGS. 1-5, the exemplary seal 10 may be a seal assembly including at least one shim or plate 12, at least one support structure or layer 14 and at least one coating or coating layer 16 coupled to one another. The shim 12 may be effective in substantially preventing the passage of substances therethrough. For example, the shim 12 may be substantially solid or otherwise substantially impervious to at least one of gases, liquids and solids at pressures and temperatures produced in turbo machinery. However, the shim 12 may also provide flexibility at pressures and temperatures produced in turbomachinery to accommodate skews or offsets in slot surfaces in the thickness T1 direction. In one embodiment, the shim 12 is a substantially solid plate-like metallic member. In some such embodiments the shim 12 may be a high temperature metallic alloy or super alloy. For example, in some embodiments the shim 12 (and/or the support structure 14) may be made from stainless steel or a nickel based alloy (at least in part), such as nickel molybdenum chromium alloy, Haynes 214, or Haynes 214 with an aluminum oxide coating. In some embodiments, the shim 12 may be made of a metal with a melting temperature of at least 1,500 degrees Fahrenheit, and more preferably at least 1800 degrees Fahrenheit. In some embodiments, the shim 12 may be made of a metal with a melting temperature of at least 2,200 degrees Fahrenheit.

An exterior sealing surface or side 22 of the shim 12 that substantially opposes the support structure 14, as shown in FIGS. 1-5, may be substantially planar (in a neutral state). As explained further below, the exterior sealing surface 22 of the shim 12 may be configured to engage or interact with a cooling high pressure air flow flowing through at least one gap or joint between at least first and second components forming a seal slot (at least in part) so that the seal 10 is forced or pressed against sealing surfaces of the first and second components in the seal slot to substantially prevent gases, liquids and/or solids from migrating through the gap or joint. As such, at least one of the shim 12 and the coating 16 (or the shim 12 and the coating 16 acting in concert) may be substantially impervious to liquids, gases and/or solids at pressures experienced in turbomachinery such that the seal 10 provides at least a low leakage rate past the seal slot.

As shown in FIGS. 1-5 the support structure 14 may be coupled to a support surface or side 24 of the shim 12 that substantially opposes the sealing surface 22. In some embodiments the support structure 14 may be metallic, such as metallic material with the characteristics described above with respect to the shim 12. The shim 12 and the support structure 14 may be formed of the same or substantially similar metallic material, and thereby include the same or substantially similar coefficient of thermal expansion (hereinafter CTE). However, the shim 12 and the support structure 14 need not be formed of the same or substantially similar material, or include the same or substantially the same CTE. It is preferable, however, that the shim 12 and the support structure 14 be configured such that any difference in CTE therebetween does not fracture, break or otherwise render a diffusion bond therebetween, as described further below, ineffective due to cyclic thermal loading of the seal 10 during use in turbomachinery. As such, the CTE of the shim 12 and the CTE of the support structure 14 may differ only to such an extent that the diffusion bond between the shim 12 and the support structure 14 is not rendered ineffective by cyclic thermal loading of the seal 10 during use in turbomachinery. Stated differently, the material of the shim 12 and the support structure 14 (or any other factor affecting CTE) may differ, but the shim 12 and the support structure 14 may be configured such that a diffusion bond therebetween is not damaged or rendered ineffective when the seal 10 is subjected to cyclic thermal loading when utilized in a seal slot of a turbine.

The support structure 14 may be a support structure, member or assembly that is capable of chemically bonding or fusing (e.g., via a diffusion bond) to the support surface 24 of the shim 12, and capable of securely mechanically coupling or affixing with the coating 16 (which is chemically bonded to the shim 12). In this way, the coating 16 may be securely mechanically coupled or affixed to the shim 12 via the support structure 14. For example, the support structure 14 may be a substantially porous metallic structure (as opposed to the substantially non-porous shim 12) that includes cavities or voids for holding portions of the coating 16 therein. The term “porous” is used herein, with respect to the support structure 14, to describe a structure, member(s) or mechanism than includes pores, channels, voids, gaps, cavities or other interior spaces that, individually and/or collectively, allow the coating 16 to extend into the support structure 14 from the top or outer surface of the support structure 14 in a direction extending towards the shim 12 and that at least some portions of the coating 16 are positioned between the sealing surface 24 of the shim 12 and at least a portion of the support structure 14 in a direction extending at least generally away from the sealing surface 24 of the shim 12, such as substantially normal to the sealing surface 24 of the shim 12. In some embodiments, the support structure 14 may be a porous metallic mesh, lattice, honeycomb or woven-type structure with interlocked, interwoven or intermingled members, fibers or portions, as shown in FIGS. 1-5.

As shown in FIGS. 1-5, at least some portions of the support structure 14 (e.g., portions of metallic mesh members or fibers) may be fused or bonded with the support surface 24 of the shim 12. In some embodiments, however, other portions of the support structure 14 may be spaced from the support surface 24 of the shim 12 (i.e., not fused or bonded to the shim 12). For example, a metallic mesh-type support structure 14 may include metallic members or fibers that include first portions that are fused or bonded to the support surface 24 of the shim 12 and second portions that are not bonded or fused to the shim 12 and, potentially, spaced from the support surface 24 of the shim 12. In this way, only a fraction or portion of the support structure 14 may be bonded or fused to the shim 12, with the remaining fraction or portion of the support structure 14 being coupled to (e.g., mechanically attached) or extending from the bonded or fused portion.

The shim 12 and at least a portion of the support structure 14 may be bonded or fused to each other such that their attachment is capable of effectively withstanding the temperature, pressure and other conditions experienced in a seal slot of a turbine. For example, the shim 12 and at least a portion of the support structure 14 may be bonded or fused in such a manner that creates a solid state chemical bond therebetween. In some embodiments, the shim 12 and at least a portion of the support structure 14 may be solid state welded to each other, such as via diffusion bonding. In some embodiments, the shim 12 and the support structure 14 may be diffusion bonded to each other by at least one high temperature braze.

The shim 12 and/or the support structure 14 of the shim 10 may include one or more protective coating (not shown) applied or positioned over or on an exterior surface thereof. For example, at least a portion of the outer surface of the shim 12, such as the sealing surface 22 or the support surface 24, and/or at least a portion of the outer surface of the support structure 14 may include at least one protective coating or layer. Stated differently, at least a portion of the outer surface of the shim 12 (e.g., the support surface 24) and/or the support structure 14 may be defined by a protective coating overlying the underlying metallic component (i.e., the metallic shim 12 or the metallic support structure 14). As such, the portion or portions of the shim 12 and/or the support structure 14 which are diffusion bonded to each other may include the protective coating or layer. For example the support structure 14 may be bonded to protective coating overlying on the shim 12 and forming the support surface 24. The protective coating(s) of the metallic shim 12 and/or the metallic support structure 14 may be configured to substantially prevent or retard oxidation of the underlying metallic component. In some embodiments, the protective coating(s) of the metallic shim 12 and/or the metallic support structure 14 may include or substantially comprise an oxide, such as chromium oxide or alumina oxide.

With the shim 12 and at least a portion of the support structure 14 bonded or fused to each other, the at least one coating 16 may be applied to the seal 10 to protect the shim 12 and support structure 14. As shown in FIGS. 1 and 2, the coating 16 may be applied to the seal 10 such that the coating 16 substantially covers or overlies at least the support structure 14 and the support surface 24 of the shim 12 (i.e., the coating extends over and into the support structure 14 of the seal 10 and thereby over the support surface 24 of the shim 12). The coating 16 may substantially fill the pores or voids of the support structure 14, and may be substantially non-porous (as opposed to the support structure 14). In some embodiments, the coating 16 may also cover or overlie the support surface 24 side and the side edges of the seal 10 such that the sealing surface 22 side of the seal 10 is the only side or edge of the seal 10 not covered by, or contains, the coating 16.

The coating 16 may be one or more coating material that is/are effective in substantially preventing chemical interaction and substantially limiting thermal interaction of at least the metallic shim 12 (and, potentially, the support structure 14) when the seal 10 is utilized in a seal slot of a turbine, such as a seal slot formed by components of a high temperature gas turbine, such as stator components. As explained further below, the coating 16 on the support structure 14 may be configured to sealingly engage first and second sealing surfaces of first and second components that form a seal slot to substantially prevent gases, liquids and/or solids from migrating through a gap or joint between the first and second components. In this way, the coating 16 may be effective in substantially preventing silicide formation, oxidation, thermal creep and/or wear of at least the metallic shim 12 (and, potentially, the support structure 14) during use of the seal 10 in such a seal slot of a turbine. Stated differently, the coating 16 allows for metallic-based seals, such as the seal 10 with the one or more metallic shim 12 (and, potentially, the support structure 14), to be utilized in high temperature gas turbine applications. In some embodiments, the coating 16 may be a ceramic, glass or enamel material that is effective in protecting (e.g., preventing or reducing oxidation, silicide formation, thermal creep, wear, etc.) at least the metallic shim 12 and/or the support structure 14.

In some embodiments, the coating 16 may be formed of a crystalline, glassy or glass ceramic composite. In some such embodiments, the coating 16 may include metal oxides, nitrides or oxynitrides. For example, the coating 16 may include stabilized or unstabilized zirconia, alumina, titania, alkaline earth and/or rare earth zirconates, titanates, aluminates, tantalates and niobates, tungstates, molybdates, silicates borates, phosphates, silicon nitride, silicon carbide, intermetallic compounds such as MAX phase materials (Ti2AlC) and combinations thereof. In some embodiments, the coating 16 may be formed of a high temperature porceain enamel composition. For example, the coating 16 may include alkali/alkali earth alumino boro phosphor silicate glasses and fillers. The coating 16 (whether a ceramic, glass or enamel material) may include the required high temperature melt and flow properties to provide optimum stability and compliance at the operating conditions of the seal 10.

In some embodiments, the coating 16 (and/or the protective coating described herein) may be formed on the metallic shim 12 (and/or the metallic support structure 14) by, at least in part, the diffusion of selected species into, and/or reaction with, the metallic shim 12 (and/or the metallic support structure 14) to form metal silicide(s) and/or at least one oxide layer on the metallic shim 12 (and/or the metallic support structure 14). The metal silicide(s) formed by the diffusion/reaction of the selected species and the metallic shim 12 (and/or the metallic support structure 14) may be resistant to oxidation. The one or more oxide layer formed by the diffusion/reaction of the selected species and the metallic shim 12 (and/or the metallic support structure 14) may include negligible oxygen diffusion capacity therethrough, thus protecting the metallic shim 12 (and/or the metallic support structure 14). For example, Si may be utilized and diffused into, and/or reacted with, the metallic shim 12 (and/or the metallic support structure 14). In some embodiments, the selected species for forming the metal silicide(s) and/or the at least one oxide layer may include Al, Si, B, alloys thereof, or combinations thereof. In some embodiments, the metallic shim 12 (and/or the metallic support structure 14) may be formed of or include a refractory metal, such as Mo, W, alloys thereof, or combinations thereof, and the refractory metal shim 12 (and/or support structure 14) may include a silicide layer and/or an alumina protective layer as at least a portion of the coating 16. In some embodiments, the metal silicide(s) and/or the at least one oxide layer may be formed by reaction with a packed bed of the selected species (e.g., in a powder or like form) and the metallic shim 12 (and/or the metallic support structure 14) at high temperatures (i.e., a pack siliciding/oxide layer method). In other embodiments, the metal silicide(s) and/or the at least one oxide layer on the metallic shim 12 (and/or the metallic support structure 14) may be formed through one or more coating of the selected species (e.g., metallic elements/alloys) through vapor phase deposition (e.g., chemical vapor deposition (CVD) or physical vapor deposition (PVD)), followed by chemical and/or heat treatment.

In some ceramic coating 16 embodiments, the ceramic coating 16 may be formed from a high viscosity castable composition, such as a castable cement (e.g., COTRONICS 904 or 989). The high viscosity castable composition may be applied on the bonded shim 12 and the support structure 14 by screen printing or toweling. After the castable composition of the coating 16 is applied to the bonded shim 12 and the support structure 14, excess coating 16 material may be removed by doctor blading to a desired or required thickness on the seal 10 (e.g., a particular amount of coating castable composition on the top or above the outer surface of the support structure 14). The applied and bladed “green” coating may be further processed to densify and chemically bond to the coating 16 material to the bonded shim 12 and the support structure 14 by curing and heat treating. The curing may set the coating 16 material, and the heat treating may densify the coating 16 material to a closed porosity state to, ultimately, form the coating 16 on the bonded shim 12 and the support structure 14. As noted above, the coating 14 may be bonded to the metallic shim 12 itself or to a protective coating overlying the metallic shim 12.

In some glass or enamel coating 16 embodiments, the coating 16 may be formed from glass or enamel based compositions in a paintable form. The paintable form glass or enamel based compositions may include a relatively low viscosity that allows the glass or enamel based compositions to be painted on the bonded shim 12 and the support structure 14, or the bonded shim 12 and the support structure 14 may be dip or spray coated with the glass or enamel based compositions. In some embodiments, the glass or enamel based compositions may include a solvent or the like to decrease the viscosity of the compositions. After the glass or enamel based compositions are applied to the bonded shim 12 and the support structure 14, the compositions may be dried, such as to remove solvents from the applied compositions. After drying of the applied glass or enamel based compositions on the bonded shim 12 and the support structure 14, the compositions may be heat treated to form a coating 16 of a substantially dense, smooth, glassy coating that is chemically bonded and mechanically coupled to the shim 12 and the support structure 14.

In some alternative embodiments, the coating 16 composition may be formulated as precursor. For example, the coating 16 composition be formed of a gellable sol from precursor slats such as nitrates, carboxylates, alkoxides with a certain fraction added as fillers. The gellable sol may be applied to bonded shim 12 and the support structure 14 to form the coating 16 by any of the aforementioned processes.

As discussed above, the coating 16 (whether it be ceramic, glass or an enamel) may be applied to the metallic shim 12 and the metallic support structure 14 such that the coating 16 is, at least initially, chemically bonded or coupled directly to the metallic shim 12 (e.g., over or on the support surface 24 of the metallic shim 12) and/or the metallic support structure 14. As also noted above, the metallic shim 12 and/or metallic support structure 14 may include a protective coating. In some such embodiments, the coating 16 may be chemically bonded to the protective coating (thereby indirectly chemically bonded to the metallic shim 12 and/or metallic support structure 14).

The coating 16 may substantially fill voids of the support structure 14 (including any or spaces between the support structure 14 and the shim 12, as explained further below) and extend over the top or outer surface of the support structure 14 (to thereby cover the support surface 22 of the shim 12). As explained further below, the support structure 14 may be chemically bonded to the shim 12 and configured to mechanically couple with the coating 16. In this way, the coating 16, which is effective in thermally and chemically insulating the metallic shim 12, may be at least initially both chemically bonded and mechanically fixed to the metallic shim 12 and the metallic support structure 14.

In order for the coating 16 to continuously or reliably provide protection to at least the metallic shim 12 (and, potentially, the metallic support structure 14), the support structure 14 may be effective in maintaining the attachment or coverage of the coating 16 over the metallic shim 12—such as sides, edges or portions of at least the metallic shim 12 that may be exposed to during use of the seal 10 in a seal slot of a turbine. For example, the chemical bond or coupling between a ceramic or glass coating 16 and the metallic shim 12 and metallic support structure 14 (or a protective coating thereon) may not withstand the thermal cycling of the shim 12 (occurring during use of the shim 12, for example) due to the thermal mismatch between the ceramic or glass coating 16 and the metallic shim 12 and metallic support structure 14. As shown in FIGS. 1 and 2 and explained above, the metallic support structure 14 may be bonded or fused to the metallic shim 12 and the coating 14 may be provided at least throughout or within voids of the support structure 14. More specifically, however, the coating 14 may also extend or be positioned, at least partially, between the shim 12 and portions of the support structure 14 in a direction extending at least generally away from the sealing surface 22 of the shim 12. In some embodiments, the coating 14 may be positioned, at least partially, between the shim 12 and the individual members, fibers or portions of the support structure 14 (or portions thereof) in a direction extending substantially normal to the support surface 24 of the shim 12. The coating 14 thereby may be provided or extend substantially about fibers, members or portions of the support structure 14 (but for the portions thereof that are fused or bonded to the shim 12). In this way, because at least some of the fibers, members or portions of the support structure 14 are bonded or fused to the metallic shim 12 and portions of the coating 14 are positioned between the shim 12 and portions of the support structure 14, the support structure 14 provides a mechanical attachment of the coating 14 to the metallic shim 12 that prevents the coating 14 from detaching or decoupling from the shim 12. For example, if the chemical bond between the coating 16 and the metallic shim 12 and/or the metallic support structure 14 (or a protective coating thereon) fails due to thermal mismatch therebetween, the positioning of the coating 16 substantially about the fibers, members or portions of the support structure 14 (e.g., over the outer surface of the support surface 24 and between portions of the support surface 24 and the shim 12) provides a mechanical attachment that prevents the coating 16 from becoming detached or decoupled from the metallic shim 12 (via the metallic support structure 14).

As noted above, portions of the coating 14 may be positioned between the metallic shim 12 and portions of the support structure 14 that are spaced from the metallic shim 12 (e.g., portions that are not bonded or fused to the metallic shim 12, but rather extend from, or are coupled to, portions that are that are bonded or fused to the metallic shim 12). Portions of the coating 14 may also be positioned between the metallic shim 12 and portions of the support structure 14 that are bonded or fused to the metallic shim 12. As shown in FIGS. 1 and 5, for example, the fibers, members or portions of the support structure 14 that are bonded or fused to the metallic shim 12 may include or define a shape that provides or forms a space or void 26 between the fibers, members or portions of the support structure 14 and the support surface 24 of the shim 12. In the exemplary illustrated embodiment in FIGS. 1, 4 and 5, the fibers, members or portions of the support structure 14 that are bonded or fused to the support surface 24 of the shim 12 are substantially circular in cross-section such that a space or void 26 is formed between the respective fibers, members or portions of the support structure 14 and the support surface 24 of the shim 12. Other configurations of the support structure 14 that form such a space or void 26 between the support surface or side 24 of the shim 12 and the support structure 14 (when bonded) may be utilized. In this way, the shape or configuration of the fibers, members or portions of the support structure 14 may allow the coating 14 to be positioned between bonded portions of the support structure 14 and the sealing surface or side 24 of the shim 12 (e.g., in a direction extending generally away from, or substantially normal to, the sealing surface 24).

FIG. 6 illustrates a cross-sectional view of an exemplary slot seal assembly 110 positioned within an exemplary seal slot to seal an exemplary junction between turbine components, such as stator components. The exemplary slot seal assembly 110 is substantially similar to the exemplary slot seal assembly 10 of FIGS. 1-5 described above, and therefore like reference numerals preceded with “1” are used to indicate like aspects or functions, and the description above directed to such aspects or functions (and the alternative embodiments thereof) equally applies to the exemplary slot seal assembly 110. Specifically, FIG. 6 shows a cross-section of a portion of an exemplary turbomachine including an exemplary first turbine component 142, an adjacent exemplary second turbine component 144, and an exemplary composite slot seal 110 installed in the seal slot formed by the first and second components 142, 144. The first and second turbine components 142, 144 may be first and second stator components, such as first and second nozzles of first and second stators, respectively. In other embodiments, the first and second components 142, 144 may be any other adjacent turbomachinery components, such as stationary or translating and/or rotating (i.e., moving) turbine components. Stated differently, the exemplary composite slot seals 10, 110 described herein may be configured for, or used with, any number or type of turbomachinery components requiring a seal to reduce leakage between the components.

The cross-section of the exemplary components 142, 144 and exemplary composite slot seal 110 illustrated in FIG. 6 is taken along a width of the structures, thereby illustrating an exemplary width and thickness/height of the structures. It is noted that the relative width, thickness and cross-sectional shape of the structures illustrated in FIG. 6 is exemplary, and the structures may include any other relative width, thickness and cross-sectional shape. Further, the length of the structures (extending in-out of the page of FIG. 6) may be any length, and the shape and configuration of the structures in the length direction may be any shape or configuration. It is also noted that although only two exemplary turbine components 142, 144 forming one seal slot is shown, a plurality of components may form a plurality of seal slots that are in communication with one another. For example, a plurality of turbine components may be circumferentially arranged such that seal slots formed thereby are also circumferentially arranged and in communication with one another. In such embodiments, the slot seals 10, 110, 210 according to the present disclosure may be configured to span a plurality of seal slots to seal a plurality of gaps or junctions and thereby reduce leakage between a plurality of turbine components.

As shown in FIG. 6, the first and second adjacent turbine components 142, 144 may be spaced from one another such that a junction, gap or pathway 190 extends between the first and second adjacent components 142, 144, such as stators. Such a junction 190 may thereby allow flow, such as airflow, between the first and second turbine components 142, 144. In some configurations, the first and second turbine components 142, 144 may be positioned between a first airflow 150, such as a cooling airflow, and a second airflow 160, such as hot combustion airflow. It is noted that the term “airflow” is used herein to describe the movement of any material or composition, or combination of materials or compositions, translating through the junction 190 between the first and second turbine components 142, 144.

To accept a seal that spans across the junction 190, and thereby block or otherwise cutoff the junction 190, the first and second adjacent components 142, 144 may each include a slot, as shown in FIG. 6. In the exemplary illustrated embodiment, the first component 142 includes a first seal slot 170 and the second component includes a second seal slot 180. The first and second seal slots 170, 180 may have any size, shape, or configuration capable of accepting a seal therein. For example, as shown in the illustrated exemplary embodiment in FIG. 6, the first and second seal slots 170, 180 may be substantially similar to one another and positioned in a mirrored relationship to define together a net slot or cavity that extends from within the first component 142, across the junction 190, and into the second component 144. In this manner, the pair of first and second seal slots 170, 180 may jointly form a cavity or seal slot to support opposing portions of a seal such that the seal 110 passes through the junction 190 extending between the adjacent components 142, 144.

In some arrangements wherein the first and second turbine components 142, 144 are adjacent, the first and second seal slots 170, 180 may be configured such that they are substantially aligned (e.g., in a mirrored or symmetric relationship). However, due to manufacturing and assembly limitations and/or variations, as well as thermal expansion, movement and the like during use, the first and second seal slots 170, 180 may be skewed, twisted, angled or otherwise misaligned. In other scenarios, the first and second seal slots 170, 180 may remain in a mirrored or symmetric relationship, but the relative positioning of the first and second seal slots 170, 180 may change (such as from use, wear or operating conditions). The term “misaligned” is used herein to encompass any scenario wherein seal slots have changed relative positions or orientations as compared to a nominal or initial position or configuration.

With respect to the exemplary first and second seal slots 170, 180 of the exemplary first and second turbine components 142, 144 and the exemplary seal 110 of FIG. 6, in a misaligned configuration (not shown) the exemplary seal 110 is preferably flexible to account for the misalignment and maintain sealing contact of the coating 116 with the first and second seal slots 170, 180 to effectively cut off or eliminate the junction 190 extending between the first and second turbine components 142, 144 to thereby reduce or prevent the first and second airflows 150, 160 from interacting. More particularly, as shown in FIG. 6 the first and second airflows 150, 160 may interact with the junction 190 such that the first airflow 150 is a “driving” airflow that acts against the exterior sealing surface 122 of the shim 112 of the seal 110 to force the coating 116 of the seal 110 against first side surfaces 135, 145 of the first and second seal slots 170, 180, respectively. In such scenarios, the seal 110 (and/or coating 166) may be preferably sufficiently flexible to deform (e.g., elastically) as a result of the forces applied by the first airflow 150 (e.g., above that applied by the second airflow 160) to account for any misalignment between the first and second seal slots 170, 180, but sufficiently stiff to resist being “folded” or otherwise “pushed” into the junction 190. Stated differently, in such a scenario, the exemplary seal 110 may be preferably sufficiently flexible, but yet sufficiently stiff, to maintain sealing engagement of the coating 116 of the shim 112 with the first side surfaces 135, 145 via the forces of the first airflow 150. For example, the metallic shim 112, metallic support structure 114, and the coating 116 may be configured to conform to irregularities on the seal slot contact surfaces 135, 145 during use of the turbine. In some such embodiments, the coating 116 may be a glass insulating coating with a transition temperature (Tg) similar to that of the operating temperatures of the turbine/seal 110 so that the glass coating 116 becomes soft or deformable at operating temperatures to facilitate deformation an contouring of at least the coating 116 to the first side surfaces 135, 145. In addition to being sufficiently flexible (in all directions) to effectively seal the junction 190 in misalignment scenarios, as described above, the exemplary seal 110 may preferably be sufficiently stiff to satisfy assembly requirements.

The size of the seal 110 may be any size, but may be dependent upon, or at least related to, the components 142, 144 in which the seal 110 is installed. The thickness T1 of the exemplary seal 110 may be less than the thickness T2 of the first and second seal slots 170, 180, and thereby the thickness T2 of the net slot created by the first and second seal slots 170, 180 when the first and second adjacent components 142, 144 are assembled. In some embodiments, the thickness T1 of the exemplary seal 110 may preferably be within the range of about 0.01 inches to about ¼ inches, and more preferably within the range of about 0.05 inches to about 0.1 inches. Similarly, the width W1 of the seal 110 may be less than the width W2 of the net slot created by the first and second slots 170, 180 of the first and second components 142, 144, respectively, and the gap 190 between the components 142, 144 when the components 142, 144 are installed adjacent to one another. In some embodiments, the width W1 of the exemplary seal 110 may preferably be within the range of about 0.125 inches to about 0.75 inches.

As shown in the illustrated embodiment in FIG. 6, for example, the seal 110 may be positioned and arranged within the seal slot (i.e., the first and second seal slots 170, 180) such that the first or cooling airflow 150 acts against the exterior sealing surface 122 of the shim 112 to force the coating 116 against the first side surfaces 135, 145 of the first and second seal slots 170, 180. Due to the impervious nature of the shim 112 and/or the coating 116, the seal 110 thereby prevent the cooling airflow 150 from migrating through the gap 190 and into the second or hot combustion airflow 160. Further, the coating 116 protects the metallic shim 112 from the high temperatures of the combustion airflow 160. In this way, at least the shape and configuration of the exterior or sealing surface of the coating 116 of the seal 110 (e.g., the surface that interacts with the exemplary first side surfaces 135, 145 or other sealing surfaces of the exemplary first and second seal slots 170, 180) may be related to the shape and configuration of the slots 142, 144 in which the seal 110 is installed. Stated differently, the shape and configuration of at least the exterior or sealing surface of the coating 116 of the seal 110, such as the contour, surface texture, etc., may be configured to ensure sealing engagement with the first and second seal slots 170, 180 in which the seal 110 is installed. For example, in the illustrated example in FIG. 6, the exterior or sealing surface of the coating 116 of the seal 110 may be substantially smooth and planar to substantially abut or otherwise substantially engage the substantially planar first side surfaces 135, 145 of the first and second seal slots 170, 180 to effectively prevent or reduce leakage of the first airflow 150 between the seal assembly 110 and the first side surfaces 135, 145 of the first and second seal slots 170, 180 and, ultimately, into the second or hot combustion airflow 160 (and to also protect the metallic shim 12 from the high temperatures of the hot combustion airflow 160). In some alternative embodiments (not shown), the shape and configuration of at least the exterior or sealing surface of the coating 116 of the seal 110 may be shaped or configured differently than that of the corresponding sealing surfaces of the first and second seal slots 170, 180 (such as the exemplary first side surfaces 135, 145 of the first and second seal slots 170, 180 illustrated in FIG. 6).

FIG. 7 illustrates a cross-sectional view of another exemplary slot seal assembly 210 according to the present disclosure. The exemplary slot seal assembly 210 is substantially similar to the exemplary slot seal assemblies 10 and 110 of FIGS. 1-6 described above, and therefore like reference numerals preceded with “2” are used to indicate like aspects or functions, and the description above directed to such aspects or functions (and the alternative embodiments thereof) equally applies to the exemplary slot seal assembly 210. As shown in FIG. 7, slot seal assembly 210 differs from seal assemblies 10 and 110 in that the seal 210 is symmetrical in the thickness direction. As such, seal assembly 210 provides for ease of installation or assembly of the seal 210 in a turbine seal slot as the seal 210 does not need to be particularly oriented in the thickness direction.

As shown in FIG. 7, both the sealing surface 222 and the support surface 224 sides of the metallic shim 12 include a metallic support structure 214 bonded thereto. In some embodiments (not shown), the support structure may 214 may extend over one or more side edges of the metallic shim 212 and onto the sealing surface 222 and the support surface 224. Similarly, both the support structure 214 bonded to the sealing surface 222 and the support structure 214 bonded to the support surface 224 of the metallic shim 212 include the coating 216 applied thereto. In some embodiments (not shown), the coating 216 may extend over one or more side edges of the metallic shim 212 and onto/into the support structure 214 bonded to the sealing surface 222 and the support structure 214 bonded to the support surface 224. The coating 216 applied on and in the support structure 214 that is bonded to the sealing surface or side 222 of the shim 210 may insulate or protect the sealing surface side 22 of the shim 212 (such as from the cooling airflow 150 discussed above with respect to FIG. 6).

The seal assemblies disclosed herein provide low leakage rate similar to that possible with tradition slot seals, such as solid metal shim seals, while eliminating the silicide formation, oxidation, thermal creep and/or increased wear concerns when applied to modern high temperature turbomachinery. Moreover, the seal assemblies disclosed herein may be less susceptible to manufacturing variations as compared to existing seals. The seal assemblies disclosed herein thus reduce leakage with low manufacturing and operational risks, and are applicable in both OEM and retrofit applications.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term “operably connected” is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

We claim:
 1. A seal assembly for positioning within a seal slot formed at least partially by adjacent turbomachinery components to seal a gap extending between the components, the seal assembly comprising: a metallic shim including a sealing surface and a support surface; a porous metallic support structure bonded to the support surface of the metallic shim; and a ceramic, glass or enamel coating extending over and within the porous metallic support structure such that the coating substantially covers the support surface side of the metallic shim and the support structure, and wherein portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure.
 2. The seal assembly of claim 1, wherein portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure in a direction extending away from the support surface to mechanically couple the coating to the metallic shim via the metallic support structure.
 3. The seal assembly of claim 2, wherein the direction extending away from the support surface is substantially normal to the support surface.
 4. The seal assembly of claim 1, wherein the metallic shim is a substantially solid metallic shim.
 5. The seal assembly of claim 1, wherein the coating is chemically bonded to the support structure.
 6. The seal assembly of claim 1, wherein at least one of the support surface of the metallic shim and the metallic support structure includes a protective outer coating configured to prevent oxidation of the respective metallic component.
 7. The seal assembly of claim 1, wherein the metallic support structure is diffusion bonded to the metallic shim via at least one braze.
 8. The seal assembly of claim 1, wherein the metallic support structure is a mesh structure.
 9. The seal assembly of claim 1, wherein portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure that are bonded to the support surface of the metallic shim.
 10. The seal assembly of claim 1, wherein portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure that are not bonded to the support surface of the metallic shim.
 11. The seal assembly of claim 10, wherein the portions of the metallic support structure that are not bonded to the support surface of the metallic shim extend from or are coupled to portions of the metallic support structure that are bonded to the support surface of the metallic shim.
 12. The seal assembly of claim 1, wherein the coating is bonded to at least one of the support surface of the shim and the support structure.
 13. The seal assembly of claim 1, further comprising: a second porous metallic support structure bonded to the sealing surface of the shim; and a second ceramic, glass or enamel coating extending over and within the second porous metallic support structure such that the second coating substantially covers the sealing surface side of the metallic shim and the second support structure, and wherein portions of the second coating are positioned between the sealing surface of the metallic shim and portions of the second metallic support structure.
 14. A method of forming a seal assembly for use within a seal slot formed at least partially by adjacent turbomachinery components to seal a gap extending between the components, the method comprising: bonding at least one portion of a porous metallic support structure to a metallic shim; applying ceramic, glass or enamel coating material to the porous metallic support structure such that the coating material overlies the support surface side of the metallic shim and the support structure, and includes portions that are positioned between the support surface of the metallic shim and portions of the metallic support structure; and densifying the ceramic, glass or enamel coating material to form a ceramic, glass or enamel coating mechanically fixed to the metallic shim via the metallic support structure.
 15. The method of claim 14, wherein bonding at least one portion of the metallic support structure to the support surface of the metallic shim includes diffusion bonding at least one portion of the metallic support structure to the support surface of the metallic shim.
 16. The method of claim 14, wherein applying ceramic, glass or enamel coating material to the porous metallic support structure comprises applying a high viscosity castable ceramic composition by screen printing or toweling.
 17. The method of claim 16, further comprising removing a portion of the ceramic composition applied to the support structure via a doctor blade, and wherein densifying the ceramic composition comprises curing and heat treating the applied ceramic composition.
 18. The method of claim 14, wherein applying ceramic, glass or enamel coating material to the porous metallic support structure comprises applying a glass or enamel based composition in a paintable form by painting, dip coating or spray coating.
 19. The method of claim 18, wherein densifying the glass or enamel based composition comprises drying and heat treating the applied glass or enamel based composition.
 20. A turbomachine comprising: a first turbine component and a second turbine component adjacent the first turbine component, the first and second turbine components forming at least a portion of a seal slot extending across a gap between the turbine components; and a seal positioned within the seal slot of the first and second turbine components and extending across the gap therebetween, the seal comprising: a metallic shim including a sealing surface and a support surface; a porous metallic support structure bonded to the support surface of the metallic shim; and a ceramic, glass or enamel coating provided on and within the metallic support structure such that the coating substantially covers the support surface side of the metallic shim and the support structure, and portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure.
 21. The turbomachine of claim 20, wherein the ceramic, glass or enamel coating of the seal is positioned against a first side of the seal slot that is collectively formed by a first side of the first turbine component and a first side of the second turbine component.
 22. The turbomachine of claim 20, wherein the metallic shim is a substantially solid metallic shim, and the porous metallic support structure is a metallic mesh structure.
 23. The turbomachine of claim 20, wherein portions of the coating are positioned between the support surface of the metallic shim and portions of the metallic support structure in a direction extending substantially normal to the support surface to mechanically couple the coating to the metallic shim via the metallic support structure. 